infringement (of trademark)

Definition from Nolo’s Plain-English Law Dictionary

Unauthorized use of a trademark or service mark (or a substantially similar mark) on competing or related goods and services. The success of a lawsuit to stop the infringement turns on whether the defendant's use causes a likelihood of confusion in the average consumer. If a court determines that confusion is likely, the owner of the original mark can prevent the second user's use of the infringing mark and sometimes collect damages.Compare: dilution